Preheat your oven to 375°F (190°C) and lightly grease a baking dish large enough to hold the peppers upright.

Rinse the quinoa thoroughly under cold water, then combine it with the vegetable broth in a medium saucepan.

Bring the broth to a boil, then reduce the heat to low, cover, and simmer for 15 minutes until the liquid is absorbed and the quinoa is fluffy.

While the quinoa cooks, heat the olive oil in a skillet over medium heat and sauté the diced onion for about 5 minutes until soft and translucent.

In a large mixing bowl, combine the cooked quinoa, sautéed onion, black beans, corn, salsa, cumin, chili powder, and garlic powder.

Stir the mixture well to ensure the spices and ingredients are evenly distributed throughout the filling.

Arrange the hollowed bell peppers in the prepared baking dish so they stand upright without tipping over.

Generously spoon the quinoa mixture into each pepper, packing it down gently to fill them completely.

Cover the dish with aluminum foil and bake for 30 minutes to allow the peppers to soften and steam.

Remove the foil, sprinkle the shredded cheese evenly over the top of each pepper, and bake uncovered for another 10-15 minutes until the cheese is melted and bubbly.

Remove from the oven, garnish with fresh chopped cilantro, and serve warm as a complete meal.